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In this photo released Friday, Feb. 15, 2013 by Miraflores Presidential Press Office, Venezuela's President Hugo Chavez, center, poses for a photo with his daughters in Havana, Cuba.

At Caracas' military hospital, the only outward signs that President Hugo Chavez is a patient inside are the motorcades that come and go and the soldiers standing guard, some of them wearing red berets.

A poster with a large photo of Chavez smiling sits atop the Dr. Carlos Arvelo Military Hospital, but it has been there since long before the socialist leader was admitted upon his return from his latest cancer treatment in Cuba.

Some of the president's supporters shout "Viva Chavez!" and "He's back!" as they drive past the hospital, which this week has become the new center of attention in Chavez's 21-month-long cancer struggle.

The government provided an update on Chavez's condition Thursday night, saying that he remained at the hospital and that "the medical treatment for the fundamental illness continues without presenting significant adverse effects."

Information Minister Ernesto Villegas read the statement on television, saying that a "respiratory insufficiency" that arose in the weeks after the surgery "persists and its tendency has not been favorable, thus it continues to be treated." The government has said Chavez is breathing through a tracheal tube.

"The patient remains in communication with his relatives, with the political team of his government and in close cooperation with his medical team," Villegas said, adding that Chavez "keeps clinging to Christ, with a maximum will to live."

The government hasn't released a single photo of Chavez since his arrival in Caracas on Monday, and that has led some Venezuelans to question whether he's actually in the hospital. Others insist he is there, just out of sight while undergoing treatment.

"There, where you see that balcony, the president is there," said Juan Carlos Hernandez, a street vendor who pointed to the ninth floor, where Chavez is said to be staying.

Hernandez, who sells snacks from a stand with a parasol, said he used to work as a military police officer and provided security at the hospital from 2004 to 2006. He said the ninth floor has a special wing with various rooms where important people are typically taken for treatment, including generals and other military officers.

The special wing of the hospital has its own private elevator, Hernandez said. "The patients are more protected because not everybody passes by."

Caravans of SUVs escorted by troops on motorcycles have arrived and left in recent days, carrying officials including Vice President Nicolas Maduro and National Assembly President Diosdado Cabello, who are among the few who say they have seen Chavez at the hospital.

Among the luxury vehicles bringing visitors was a metallic green Bentley, and those stopping by the hospital have reportedly included the president's relatives.

The government hasn't given details of any visits with Chavez at the hospital, and Bolivian President Evo Morales said Wednesday that he had met only with relatives and doctors but was unable to see Chavez himself when he visited the hospital. Speaking at the United Nations, Morales said Chavez "is in a very difficult spot with his health."

The Venezuelan leader has been undergoing cancer treatment in Cuba on and off since June 2011. He has said he has had tumors removed from his pelvic region and has undergone chemotherapy and radiation treatment.

Throughout the treatments, Chavez has not revealed the type of cancer or the location where tumors have been removed.

He hasn't spoken publicly since before his latest surgery in Cuba, on Dec. 11. The government has recently said that Chavez is undergoing more treatment for his illness but has not specified the sort of treatment.

Hospital employees declined to comment about Chavez, saying only that the floor where the president is being treated is under tight security. The hospital administration did not respond to calls seeking comment.

In addition to treating the president, the hospital continues to provide medical care to hundreds of other patients every day.

The hospital opened in 1962 and is named after Carlos Arvelo, a doctor who participated in Venezuela's independence struggle. It has a capacity of 1,000 beds and says it treats about 29,000 patients a year, of whom only about 7 percent are military personnel and the rest are civilians. The hospital has about 4,000 employees.

It is one of the main public hospitals in Caracas, and provides treatment largely to poor and middle-class patients. The hospital has one of the country's most modern intensive care units as well as an advanced kidney transplant unit.

When Chavez's return to Caracas was announced Monday, his supporters gathered outside the hospital to celebrate while holding photos of him. But as the days have passed, their numbers have dwindled.

Journalists and television cameras at the entrance have become one of the few signs of anything unusual going on, in addition to the soldiers, police and members of the presidential guard standing watch at entrances, in hallways and on nearby streets.

Juan Bonaire, who works at a bakery across the street, said that apart from the stepped-up security, the area around the hospital looks much the same as always.

The surrounding neighborhood is filled with modest homes and old, weathered buildings where there are businesses including restaurants and shops that cater to patients and hospital workers.

Near the hospital, people put up a banner Thursday with a photo of the president and the slogan: "Chavez is not a man. He is a nation that advances. We will live and triumph."